When does the ski season end? The smart answer is never, because resorts with a glacier on their ski area can offer "winter" sports virtually all year round, and because in the southern hemisphere there's a winter going on while we're having our summer.

But south of the equator you'll find ski terrain which, by and large, is vastly inferior to that in France. Since glaciers are located high in the mountains, far from the resort (and getting further away, thanks to climate change), skiing on them is a bit like taking a seaside holiday in a place where the tide never comes in.

For ordinary skiers, when the season ends depends on where they're going and who they're travelling with. For anyone planning a trip to Slovenia with Crystal, I have bad news: the company's final package trip departed on 3 March, because that country's low-altitude terrain is not snow-sure thereafter. And should you flick though the Inghams brochure, read that Saariselka is "snow-sure from November to May", and pick that resort for your late-season break, you'd be making a mistake. Lapland's popularity wanes once Santa's grotto is boarded up, and Inghams sent its last clients to Saariselka on 19 February.

It's also tricky to get to the western resorts of North America for late-season skiing, though some of them stay open into May. The big tour operators offer packages to only a few of such resorts, and anyway, they don't expect to make many sales at this time of year. As the man in charge of the Inghams programme, Andy Perrin, said to me this time last year: "It does become harder to sell ski holidays when the daffodils are out."

Because the late-season snow has been so good this season in western Canada and the US – Banff had its best snowfall in 40 years a couple of weeks ago – I should point out that specialist tour operators do still get skiers out there in late April and May. But even Michael Bennett of Ski Independence (who thinks Squaw Valley and Mammoth Mountain in California are good late-skiing bets now) argues against going at the very end of the season, "when lifts, restaurants and terrain begin to close, and you can feel the place shutting down".

The fact is that with the daffodils out and Easter fast approaching, the important part of the season is almost over. Which makes this a good time to consider how the winter of 2011/12 has turned out. Three factors have determined its character: the economy, snow and more snow.

Joanna Yellowlees-Bound, the CEO of Erna Low, the UK's longest-established ski business, says: "It has been a strange season, and a difficult one. Booking patterns used to be predictable, but nothing's predictable now." The traditional main booking period, from September to November, was deathly quiet in 2011 – not altogether surprisingly, when Standard & Poor seemed intent on reducing the global economy to junk status.

Troublingly, it wasn't just bookings which were down; there was a sharp drop in the number of searches for "ski holidays" on the internet, too. The fact that hardly any snow fell in the Alps during the pre-season seemed to come as something of a relief to skiers alarmed by economic uncertainty, says Yellowlees-Bound. "It was as if they were glad that the decision that they weren't going skiing had been made for them by the weather."

But everything changed with the snow that fell in the Alps in the first week of December and again, copiously, in the following week. "There was this sudden switch, with the snow wiping out people's anxiety," Yellowlees-Bound says. "And bookings for December and January were very good, particularly in Val Thorens." She says she is happy that, overall, sales have been at about the same level as last season.

Erna Low is unusual in that it is essentially a rental company offering ski-resort property in France on an ad hoc basis: that represents more than 80 per cent of its business. Unlike the mainstream ski package-holiday companies such as Crystal and Inghams, it doesn't have a stock of accommodation and aircraft seats bought in advance. Those commitments put the package companies in an exposed position when the market declines, which it has done in each of the past three seasons. With the number of ski holidays sold having declined from 1.2 million in 2007/8 to 910,000 last season, Crystal and the other companies have reduced their capacity, and made other efforts to protect themselves. To limit the risk of having to sell beds and seats at reduced prices during the season, and to encourage early sales, Crystal and Inghams offered an unprecedented range of pre-season deals for 2011/12, mostly available only until December.

The strategy proved successful. Simon Cross, who as managing director of TUI Ski is in charge of Crystal, the UK market leader, describes himself as "very, very pleased" with its results. The Crystal Ski Plus product was not new, but the programme was broadened this season, and the starting price for the holidays was £395, including a lift pass and equipment rental. "The packages were only available until the end of November," Cross says, "but they were very good value and resonated with the market. We saw significant growth in that product, and it gave us a very good start to the booking season. Then, when the snow fell in early December, the market took off again."

For the months of January and February, Cross says, Crystal sold all of its beds in a handful of the popular Alpine resorts. He couldn't have sold a holiday at a discount if he had wanted to.

Though in marketing terms the situation in Ski Independence's North American domain was similar, the weather was different. Anxiety about the lack of snow lasted much longer in the US than it did in the Alps. The first snowfalls came only in mid-January, and it wasn't until February that the slopes were in really good shape. "There was a very slow start to the season in Colorado," says Michael Bennett, "partly because we had to advise people against going there."

But at Whistler, in British Columbia, conditions were better – and so were the incentives. "The resort put together some great deals, one of which had to be booked by 30 August," says Bennett. "It was done in conjunction with Air Canada, and offered a 50 per cent discount at the Fairmont Chateau Whistler. These were the best deals I've ever seen at Whistler." The result? Ski Independence's business there is up by 30 per cent this season, and not from a low base. "No, we're probably the biggest UK tour operator in the resort," Bennett says. He, too, is pleased with how the season has gone. "We are happy; we're up on last year, and we're looking at further growth."

Even happier is TUI's Simon Cross. "Last season was difficult: we had problems with the calendar over Christmas and the New Year. Easter came too late, and there was a serious lack of snow in the Alps. But we did well, year on year, then; this season we've built on that with strong, single-figure growth," he says. What have been the notable successes? "Well, we evolved the Ski Plus concept, with Ski Plus Extra, which includes bar credits and packed lunches: that did particularly well. Then we reintroduced Finland to the Crystal programme, and that has been successful. Business has been good in all the three main destinations [France, Austria, Italy], particularly in western Austrian resorts such as Ischgl and Obergurgl."

"The downside? Switzerland has suffered, obviously. You don't get much après-ski for your money there, now that the Swiss franc is so strong. And Bulgaria is having problems, too. It's the sort of place to which a first- or second-year skier will go, and there aren't a lot of them around in the current economic climate."

Cross also counts as a success the launch of Sochi in Russia, the site of the 2014 Winter Olympics, as a new destination, even though "only a handful of people" have chosen to go there. "We knew it would be a slow burn, attractive only to the pioneers, but we wanted to get in early," he says. "We'll definitely continue with it next year, and it will be better. At the moment, it's a very impressive construction project."